Determination of the X-ray structure of the snake venom protein omwaprin by total chemical synthesis and racemic protein crystallography.
Publication Type:Journal Article
Source:Protein Sci, Volume 19, Issue 10, p.1840-9 (2010)
Keywords:Amino Acid Sequence, Animals, Antimicrobial Cationic Peptides, Bacillus megaterium, Chromatography, High Pressure Liquid, Circular Dichroism, Crystallography, X-Ray, Elapid Venoms, Mass Spectrometry, Microscopy, Electron, Scanning, Models, Chemical, Models, Molecular, Molecular Sequence Data, Protein Conformation, Stereoisomerism
<p>The 50-residue snake venom protein L-omwaprin and its enantiomer D-omwaprin were prepared by total chemical synthesis. Radial diffusion assays were performed against Bacillus megaterium and Bacillus anthracis; both L- and D-omwaprin showed antibacterial activity against B. megaterium. The native protein enantiomer, made of L-amino acids, failed to crystallize readily. However, when a racemic mixture containing equal amounts of L- and D-omwaprin was used, diffraction quality crystals were obtained. The racemic protein sample crystallized in the centrosymmetric space group P2(1)/c and its structure was determined at atomic resolution (1.33 A) by a combination of Patterson and direct methods based on the strong scattering from the sulfur atoms in the eight cysteine residues per protein. Racemic crystallography once again proved to be a valuable method for obtaining crystals of recalcitrant proteins and for determining high-resolution X-ray structures by direct methods.</p>